Abstract:

An electrical switch includes a rotary switch actuator device, and an
actuator locking device. The actuator locking device inhibits the
rotation of the rotary switch actuator device when the contacts of the
switch are closed. Only when the operator tries to open the switch with
an operating handle and the contacts do actually open, a lock release
device will release the actuator locking device, and allow the operator
to move the operator handle to the position corresponding to the open
condition. When the contacts do not open, e.g., because they are welded,
the actuator locking device will remain locked and the handle movement is
blocked. This provides a robust and safe switch that never gives a false
"OFF" indication.

Claims:

1. A switch comprising:a rotary switch actuator device, operated from an
operating handle,an actuator locking device, which substantially inhibits
the rotary switch actuator device to change position when the actuator
locking device is in its locked condition,a switch contact pair
comprising a movable contact and a respective opposite contact for mutual
contact, the movable contact being connected to the rotary switch
actuator device,the switch comprises a lock release device, acting on the
actuator locking device,the movable contact is operated from the rotary
switch actuator device via an intermediate mechanical connection,the
movable contact provides mechanical feedback to the lock release
device,the actuator locking device is automatically locked when the
switch is activatedthe actuator locking device is released by the lock
release device.

2. A switch according to claim 1, wherein the lock release device is
mechanically connected to the movable contact.

3. A switch according to claim 2, wherein the lock release device
comprises a lock release spring,the lock release spring being charged
when the switch is activated,the lock release spring being uncharged when
the movable contact is released from the opposite contact when the switch
is deactivated, while the lock release spring stays charged when the
movable contact is not released from the opposite contact.

4. A switch according to claim 1, wherein the switch further comprises a
driver, the driver is mechanically fixed to the lock release device, and
the driver mechanically brings the movable contact in contact with the
opposite contact when the switch is activated.

6. A switch according to claim 1, whereinthe rotary switch actuator device
comprises a recess,the actuator locking device comprises a locking
element,the locking element is moved into the recess to lock the actuator
locking device and thus substantially inhibits the rotary switch actuator
device to rotate.

7. A switch according to claim 6, whereinthe recess of the rotary switch
actuator device is a half-circular recess,the locking element of the
actuator locking device comprises a shaft with a half-circular section,
the half-circular section of the actuator locking shaft is turned into
the half-circular recess to lock the actuator locking device and thus
substantially inhibits the rotary switch actuator device to rotate.

8. A switch according to claim 7, wherein the shaft with the half-circular
section comprises a shaft spring element, the shaft spring element is
charged when the half-circular section is turned out of the half-circular
recess and the shaft spring element is uncharged when the half-circular
section is turning into the half-circular recess.

9. A switch according to claim 1, wherein the rotary switch actuator
device comprises an actuator spring element, which forces the rotary
switch actuator device into a clear return position when the movable
contact is not in contact with the opposite contact.

10. A switch according to claim 1, wherein the rotary switch actuator
device comprises:a driving shaft connected mechanically to the operating
handle,a switch shaft,the driving shaft acts on the switch shaft,wherein
the action of the driving shaft on the switch shaft gives a direct
mechanical action to the switch shaft when the handle is moved in the
direction to activate the switch, whereas the action of the driving shaft
on the switch shaft gives a mechanical action to the switch shaft, only
after the driving shaft has been rotated over a minimum angle
corresponding to a mechanical tolerance between the driving shaft and the
switch shaft when the handle is moved in the direction to deactivate the
switch.

11. A switch according to claim 10, wherein the driving shaft and the
switch shaft comprise a cylindrical interface surface, and the mechanical
tolerance comprises a recess in one facing surface of the driving shaft
and the switch shaft and an extension on the other facing surface of the
driving shaft and the switch shaft.

12. A switch according to claim 11, wherein the rotary switch actuator
device comprises a switch shaft spring between the driving shaft and the
switch shaft, which causes the driving shaft to return to a clear return
position when the handle is not operated.

13. A switch according to claim 1, wherein the operating handle is mounted
on an extension shaft.

14. A switch according to claim 1, comprising at least two contact pairs,
each of the at least two contact pairs, having a corresponding actuator
locking device acting on the rotary switch actuator device, and each of
the at least two contact pairs, having a corresponding lock release
device acting on the corresponding actuator locking device.

Description:

[0002]The invention relates to a electrical switch comprising a rotary
switch actuator device, operated by an operating handle, an actuator
locking device, which substantially inhibits the rotary switch actuator
device to change position when the actuator locking device is in its
locked condition and a switch contact pair comprising a movable contact
and a respective opposite contact for mutual contact, the movable contact
being connected to the rotary switch actuator device.

BACKGROUND INFORMATION

[0003]Such a switch is known from US patent application US 2006/0278516.
The known electrical switch device comprises a body upon which is mounted
a hand lever that rotates about a main axis, cooperating with a
transmission shaft able to control the opening or the closing of
electrical contacts of the electrical switch device and elastic linking
means between the hand lever and the transmission shaft. The device also
comprises means for locking the rotation of the hand lever with respect
to the body, used when an angular divergence between the hand lever and
the transmission shaft exceeds a specified threshold. The purpose of the
know patent application is to limit the damage to the hand lever and to
the electrical device when an operator attempts to return the hand lever
to its "OFF" position whilst the contacts are welded and to prevent the
beginning of electrical arcing if the operator should succeed in
unsticking the contacts when rotating the hand lever.

[0004]The known switch has the disadvantage that its function relies fully
on the performance of the elastic linking means, which shall be stiff
enough for joining together the rotation of the hand lever and the shaft
support in normal operation, and at the same time flex sufficiently when
a rotational torque is applied to the hand lever while the shaft support
is immobilized due to a welding between the contacts. These essentially
conflicting requirements can cause the locking mechanism to malfunction
after repetitive use, with the effect that a dangerous situation can
arise in which it is possible to rotate the hand level to an
"OFF"-position while the contacts are still closed, i.e., actually in the
"ON"-position. It is a further disadvantage of the known switch that it
puts tight requirements on the strength of the locking device, its
corresponding parts in the body of the switch (the teeth) and the
protuberance of the hand lever. This limits the maximum force that the
device can withstand when the operator tries with a lot of force to
unstick the contacts by applying a large rotational torque on the hand
lever. Moreover, the known switch does not guarantee that the position of
the hand lever is always clearly indicating whether the switch is
actually "ON" or "OFF", i.e., when the contacts are closed or open
respectively.

SUMMARY OF THE INVENTION

[0005]The present invention aims to provide a robust switch that never
gives a false "OFF" indication, also not when the contacts are welded,
and has a long lifetime. The invention aims at providing a construction
which can withstand large forces without damaging the switch and
especially without the risk of damaging the contacts. The invention
further aims at providing clear indications of the true electrical
condition of the switch, i.e. whether the contacts are closed or open,
and especially when the contacts are closed and a erroneous
"ON"-indication would lead to serious danger.

[0006]Hereto the switch according to the present invention is
characterised in that the switch also comprises a lock release device,
acting on the actuator locking device, the movable contact is operated
from the switch actuator device via an intermediate mechanical
connection, the movable contact provides (mechanical) feedback to the
lock release device, the actuator locking device is automatically locked
when the switch is activated, i.e., turned to "ON", and the actuator
locking device is released by the lock release device.

[0007]In one embodiment, the lock release device is mechanically connected
to the movable contact, such that the lock release device inhibits
release of the actuator locking device when the movable contact is in
contact with the opposite contact. The mechanical connection assures that
the condition of the lock release device is always a direct and true
indication of the condition of the electrical contact.

[0008]In a further embodiment, the lock release device comprises a lock
release spring, the lock release spring being charged when the switch is
activated, and the lock release spring being uncharged when the movable
contact is released from the opposite contact when the switch is
deactivated, while the lock release spring stays charged when the movable
contact is not released from the opposite contact due to an obstruction
of any kind (such as welding). In case the contacts are opening, this
spring causes the lock release device to release the actuator locking
device. In case the contacts are not opening, the lock release device can
not release the actuator locking device, as it is mechanically held in a
fixed position corresponding to the "ON" condition of the electrical
switch.

[0009]In a further embodiment, the switch further comprises a driver,
which is mechanically fixed to the lock release device, and the driver
mechanically brings the movable contact in contact with the opposite
contact via one or more intermediate mechanical connects when the switch
is activated. The driver thus serves as a mechanical interface to the
movable contact.

[0010]Preferably, the lock release device makes a substantially linear
movement. This allows to transfer a movement in one plane to a movement
in a plane in another orientation, e.g., perpendicular to it, in a robust
way allowing to withstand large forces. The movement of the switch
actuator device and the lock release device can thus be in another
orientation than the movement of the movable contact.

[0011]In a further embodiment, the rotary switch actuator device comprises
a recess, the actuator locking device comprises a locking element, and
the locking element is moved into the recess to lock the actuator locking
device and thus substantially inhibits the rotary switch actuator device
to rotate. This is an effective way of obstructing the rotation of the
rotary switch actuator.

[0012]Preferably, the recess of the rotary switch actuator device is a
half-circular recess, and the locking element of the actuator locking
device comprises a shaft with a half-circular section, which is turned
into the half-circular recess to lock the actuator locking device. The
mechanical strength of such a rotary lock system is much better than that
of a linear pin-in-hole lock, as these locking shafts can withstand large
forces. It also provides a stiff construction. Moreover, such a the
rotary lock system requires relatively little energy for releasing.

[0013]The shaft with the half-circular section preferably comprises a
shaft spring element, which is charged when the half-circular section is
turned out of the half-circular recess and which is uncharged when the
half-circular section is turning into the half-circular recess. This
assures that the shaft always returns to a well-defined position.

[0014]In an embodiment, the rotary switch actuator device comprises an
actuator spring element which causes the rotary switch actuator device to
return to a clear return position when the movable contact is not in
contact with the opposite contact. The spring element prevents the rotary
switch actuator to take an in-between position in which it is not clear
whether the switch is "ON" or "OFF". The spring element also prevents the
contacts themselves to take intermediate positions, which further
contributes to the safety of the switch.

[0015]Moreover, the rotary switch actuator device preferably comprises a
driving shaft connected mechanically to the operating handle and a switch
shaft, with the driving shaft acting on the switch shaft, and wherein the
action of the driving shaft on the switch shaft gives a direct mechanical
action to the switch shaft when the handle is moved in the direction to
activate the switch, whereas the action of the driving shaft on the
switch shaft gives a mechanical action to the switch shaft only after the
driving shaft has been rotated over a minimum angle due to a mechanical
tolerance between the driving shaft and the switch shaft when the handle
is moved in the direction to deactivate the switch. The direct action
when turning "ON" the switch is required by the operators of such
switches. The delayed action when turning "OFF" the switch has no
negative side effect when the switch functions normally, i.e., when the
contacts are fully separated. However, when the contacts can not be fully
separated, it gives the operator an indication that the switch actuator
itself is still in good order, but the electrical switch is (at least
partly) obstructed and that the contacts can not be separated. Moreover,
it allows the operator to exert some more force to try to separate the
contacts than it would when the handle would be fully fixed in position.
Also the delayed action allows the operator to interrupt a switching-off
action and leave the switch turned "ON" and the contacts closed, when he
recognizes that he was mistakenly switching off the device.

[0016]In a preferred embodiment, the driving shaft and the switch shaft
comprise a cylindrical interface surface, and the mechanical tolerance
comprises a recess in one facing surface of the driving shaft and the
switch shaft and an extension on the other facing surface of the driving
shaft and the switch shaft. This makes a robust construction which can
handle significant forces.

[0017]The rotary switch actuator device is preferably equipped with a
switch shaft spring between the driving shaft and the switch shaft, the
spring causing the driving shaft to return to a clear return position
when the handle is not operated. This gives the operator a clear and
unambiguous indication of the actual condition of the electrical switch.
The spring moment can be selected to optimally suit the application,
e.g., in case the switch is mounted in a system with a lot of friction on
the rotation of the driving shaft, the spring moment can be made large.

[0018]The operating handle can be mounted directly to the driving shaft,
but it can also be mounted on an extension shaft, such that no direct
access to the rotary switch actuator is needed. The operating handle can
be essentially any type of handle bar or knob.

[0019]In another embodiment, the switch operates two contact pairs of
fused switches, each of the contact pairs having a corresponding actuator
locking device acting on the rotary switch actuator device, and each of
the two contact pairs having a corresponding lock release device acting
on the corresponding actuator locking device. The contacts are thus
simultaneously driven, and contact separation on both sides of the fuse
is required to be able to turn the handle to the "OFF" position.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]These and other aspects of the invention will be further elucidated
and described in detail with reference to the drawings, in which
corresponding reference symbols indicate corresponding parts:

[0021]FIG. 1 a is a schematic drawing of the operation mechanism of the
switch according to a first embodiment of the present invention;

[0023]FIG. 2 is a schematic drawing of the operation mechanism of the
switch according to a second embodiment of the present invention;

[0024]FIG. 3a shows a mechanical layout of a switch according to a first
embodiment of the present invention when the switch is in the "ON"
position;

[0025]FIG. 3b shows a mechanical layout of a switch according to the first
embodiment of the present invention when the switch is in the "OFF"
position;

[0026]FIG. 4 shows a mechanical layout of a switch according to a second
embodiment of the present invention;

[0027]FIG. 5 shows a schematic drawing of a switch according to the
invention;

[0028]FIG. 6 shows again a mechanical layout of a rotary switch actuator
according to a first embodiment of the present invention, and also shows
the switch shaft and the driving shaft in detail;

[0029]FIG. 7 shows again a mechanical layout of a rotary switch actuator
according to a second embodiment of the present invention, and also shows
the switch shaft and the driving shaft in detail;

[0030]FIG. 8 shows again a mechanical layout of a rotary switch actuator
according to an embodiment of the present invention, and also shows the
switch shaft and the driving shaft in detail;

[0031]FIG. 9 shows again a mechanical layout of a switch according to a
first embodiment of the present invention, indicating the action of the
driving shaft at switching off;

[0032]FIG. 10 shows again a mechanical layout of a switch according to a
second embodiment of the present invention, indicating the action of the
driving shaft at switching off.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033]FIG. 1a is a schematic drawing of the operation mechanism of the
switch. A lever 101 rotates around an axis A which is mounted in the
switch housing. This lever 101 connects to a second lever 102 through a
joint B, and the second lever 102 drives a slider 103. The slider 103
makes a linear movement along the line through a joint C and a pivot
point D. The slider connects through the pivot point D to another lever
104, which again drivers another lever 105, which is pivoting in the
housing around a shaft point F. In the drawing, the rotation of lever 105
is in a plane perpendicular to the plane in which lever 101 rotates, but
these planes can also be in another orientation, e.g., in the same plane.
Lever 105 drives a movable contact K via intermediate levers 106, 107,
109, 110, 111, connectors G, H, N, L, and a pretensioned spring 108,
e.g., a leaf spring as drawn in FIG. 1b. The movable contact K can thus
be moved in contact to or away from the fixed contact M. Although this
example only shows the connection to a single contact pair K, M, it would
also be possible to connect more poles to through the shaft point F. FIG.
1c shows another embodiment of the connection between pivot point D to
the movable contact K, in which connector N is changed from a moving
connector as in FIG. 1a to a fixed pivot point N, and connector H is
changed into a joint between 108, 109, 110. FIG. 1d shows yet another
embodiment of the connection between pivot point D to the movable contact
K, in which H is not directly connected to K via lever 110, but via a
sliding contact P. The sliding contact P is in contact with a slider 111
and which can move along slider 111. Slider 111 is connected between a
fixed pivot pint L and the movable contact K. The sliding contact P moves
in a guidance in slider 111. It pushes the slider to the right, thus
moving the moving contact K towards the fixed contact M, when moving
downward and pulls the slider to the left, thus moving the moving contact
K away from fixed contact M, when moving upward.

[0034]FIG. 2 is a schematic drawing of a double operation mechanism of the
switch, i.e., where contact separation is demanded on two sides. This may
be implemented when (dis-)connecting an element, such as a fuse, wherein
the switching off is effected by a simultaneous contact separation on
both sides of the element. Lever 101 is extended in diametrical direction
with lever 101', connecting to a lever 102' through a joint B', and the
lever 102' drivers a slider 103'. The slider 103' connects similarly to
the slider 103 through a pivot point D' to another lever 105', pivoting
in the housing around a shaft point F', and driving another movable
contact K' via intermediate mechanical means 106', 107', 108', 109',
110', 110', connectors G', H', N', L' and a leaf spring 108', in contact
to or away from a fixed contact M'.

[0035]FIG. 3a and FIG. 3b show the mechanical layout of the switch, where
the lever 101 is part of a rotary switch actuator 1,2 in the shape of a
disc 1 rotating around axis A. The levers 101, 102, 103, 104 and 105, of
which the function was described above, are also drawn again. The switch
is equipped with an actuator locking mechanism, which locks the rotation
of the actuator disc 1 when the contacts K,M are closed. The actuator
locking mechanism has a receiving part in the actuator disc 1, in the
form of a half-circular recess 5 in the actuator disc 1. The actuator
locking mechanism further has an actuator locking device mounted in the
housing, consisting of a rotating half-circular locking shaft 3, which
can fit in the receiving half-circular recess 5 in the actuator disc,
thus blocking the rotation of the actuator disc 1, as shown in FIG. 3a.
When the actuator disc 1 is turned from an orientation corresponding to
an open contact (FIG. 3b), the "ON" position, to an orientation
corresponding to a closed contact (FIG. 3a), the "OFF" position, the
half-circular locking shaft 3 is forced by a spring 202 to rotate into
the half-circular recess 5. This way, the rotation of the actuator disc
is automatically locked when the switch is activated, i.e., when the
contacts have been closed. Any force on the actuator disc, e.g., by an
operator trying to open the switch while it is locked, is thus led
through the locking shafts 3,3' and the switch housing, and the rest of
the switch, mechanism and contacts are free from experiencing this force.
This way, the mechanism can withstand a big force.

[0036]The orientation of the actuator disc 1 between the "ON" position and
the "OFF" position is preferable in the range of 30 to 40 degrees, in
order to give a clear indication of its position independent from the
type of operator handle being used.

[0037]The position of the actuator disc 1 is thus clearly defined when the
contacts are closed, i.e., after the switching on movement has finished.
When the switching on movement has not finished, the actuator disc is
forced back to its "OFF" position by a spring 201 acting on the actuator
disc 1, such that the actuator disc also has a clearly defined "OFF"
position. Only when both contacts are open, the "OFF" position can be
reached.

[0038]FIG. 4 shows a double mechanism in which a first half-circular
locking shaft 3 locks the actuator disc 1 with a first half-circular
recess 5, and a second half-circular locking shaft 3' locks the actuator
disc 1 with a second half-circular recess 5'.

[0039]FIG. 5 gives a schematic drawing of a switch. A handle 40 acts on
the axis A, which drives the movable contact K in contact to or away from
the fixed contact M. The handle 40 can rotate the axis A in a direction
25 or in an opposite direction 26. The handle 40 is rotated in the
direction 25 when the operator wants to activate of the switch, i.e., to
close the contacts M, K, by turning the handle to the "ON" position. The
handle 40 is rotated in the direction 26 if the operator wants to
deactivate the switch, i.e., to open the contacts, by turning the handle
to the "OFF" position. The handle 40 may be mounted directly on the
rotary switch actuator, or remotely on an extension shaft.

[0040]FIG. 6 gives a detailed view of the actuator disc, and FIG. 7 gives
a similar view for the double mechanism. The actuator disc 1 is driven by
a driving shaft 2, which is connected mechanically to the operating
handle. This driving shaft 2 acts directly on the switch shaft 1 when the
handle is moved in the direction to activate the switch, i.e., in the
clockwise direction 25 in the figures. However, the action of the driving
shaft 2 on the switch shaft 1 gives a mechanical action to the switch
shaft 1, only after the driving shaft 2 has been rotated over a minimum
angle 27 in the counterclockwise direction 26 corresponding to a
mechanical tolerance 27 between the driving shaft 2 and the switch shaft
1 when the handle is moved in the direction 26 to deactivate the switch.
The mechanical tolerance is arranged by providing the inner cylindrical
interface surface 50 of the switch shaft 1 with a recess 52, and the
outer cylindrical interface surface 51 of the driving shaft with an
extension 53. The width of the extension 53 is smaller than the width of
the recess 52, such that the mechanical tolerance is achieved.

[0041]A spring 30 is provided between the switch shaft 1 and the driving
shaft 2, keeping them in the position towards each other as shown in FIG.
5, as the spring provides a moment on the driving shaft 2 in the
direction 25. As a result, the "ON" position of the driving shaft is
clearly defined when the actuator disc is in the "ON" position, also
without an external moment on the driving shaft, i.e., when the handle is
not operated. When an external moment is applied in the "OFF" direction
26, the driving shaft 2 and the handle 40 can only be moved over a
limited angle 27 when the actuator disc is in the locked condition. After
releasing the handle, it will move back again in the "ON" position.

[0042]FIG. 8 shows an alternative construction of the cooperation of the
actuator disc 1 and the driving shaft 2. In this construction, the
mechanical tolerance is arranged by providing the inner cylindrical
interface surface 50 of the switch shaft 1 with an extension 55, and the
outer cylindrical interface surface 51 of the driving shaft 2 with an
recess 54. The width of the extension 55 is smaller than the width of the
recess 54, such that the mechanical tolerance is achieved.

[0043]FIG. 9 again shows the mechanical layout of the switch. To close the
contacts, the operator will rotate the handle in the clockwise direction,
and apart from activating the actuator locking mechanism as described
above, it also acts via the lever 4 to the slider 103, at the same time
charging (straining) a spring 203 acting on the slider 103. When the
operator wants to open the switch again, he turns the handle on the
counterclockwise direction and a projection 9 of the driving shaft 2 will
force the lever 4 to rotate in the direction 21, leading to a detachment
of lever 4 from the actuator disc 1. In the normal situation, the spring
action on the slider 103 would move the slider back to its original
position and thus also separate the contacts K,M via the mechanical
construction. If however this mechanical movement is frustrated, in
particular when the contacts are not fully separated, the slider 103 is
kept in position.

[0044]The slider 103 is extended with a lock release driver 11. The lock
release driver 11 acts on the locking shaft 3 when the spring of the
slider 103 is uncharged. The lock release driver 11 then forces the
locking shaft 3 to rotate out of the half-circular recess 5 in the
actuator disc 1, thus releasing the actuator lock and allowing the
actuator disc 1 to rotate back into the "OFF" direction 20 when the
handle is operated to turn "OFF" the switch. When the spring is charged
however, the lock release driver 11 will not release the lock, as it will
not act on the locking shaft 3. The ability for mechanical movement of
the slider 103 with its lock release driver 11 will thus determine
whether the actuator lock can be released or not. Hence, when no full
contact separation can be achieved, the slider is kept in position by the
mechanical connection to the contact, and the lock release driver will
not release the actuator lock. The actuator disc will thus stay in its
"ON" position, indicating the true condition of the contact. When full
contact separation is achieved however, the slider will be moved by the
uncharging of its spring, and the lock release driver will release the
actuator lock, thus allowing the actuator disc to rotate back into the
"OFF" position, again indicating the true position of the contact.

[0045]FIG. 10 shows the double mechanism. In that case, it will be clear
from the description above that the release of both actuator locking
devices 3,5 and 3',5' is needed for allowing the actuator disc to move to
an "OFF" position. It will thus only indicate an "OFF" situation when all
contacts are fully separated.

[0046]It should be noted that the above-mentioned embodiments illustrate
rather than limit the invention, and that those skilled in the art will
be able to design many alternative embodiments without departing from the
scope of the appended claims. E.g., the half-circular section 3 of the
locking element can have rounded corners, or be another fraction of a
circle-segment, without departing from the scope of the invention and the
appended claims.

[0047]In the claims, any reference signs placed between parentheses shall
not be construed as limiting the claim. The word "comprising" does not
exclude the presence of elements other than those listed in a claim. The
word "a" or "an" preceding an element does not exclude the presence of a
plurality of such elements.